<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>三行两列布局</title>
    <style>
        div {
            text-align: center;
            line-height: 100px;
            width: 100px;
            height: 100px;
            border: 2px red solid;
            margin: 100px 100px;/*相邻两个元素都设置了外边距,那么外边距会重合*/
        }

        div:nth-child(2) {
            color: red;
        }
    </style>
</head>
<body>
<div>1</div>
<div>2</div>
<div>3</div>
</body>
</html>